Question

During an isothermal expansion, a confied ideal gas does -150J of work against its surroundings. This implies that

• A. 150J of heat has been removed from the gas
• B. 300J of heat has been added to the gas
• C. no heat is transferred because the process is isothermal
• D. 150J of heat has been added to the gas.

Answer 1

The correct option is D 150J of heat has been added to the gas.

From the first law of Thermodynamics.

$\Delta V=Q+W$

for isothermal process, $\Delta V=0$

therefore $Q=-W$

Given $W=-150$

$\therefore$ $Q=+150$

Q is possible meaning heat is added to the gas.

Option D.